Foam generator



March 4, 1969 MCDQUGALL, 3,430,865

FOAM GENERATOR Original Filed Feb. 9. 1966 WATER 30 i 35 37 42 32 DETERGENT,

FIG. 3

INVENTOR H FRANKLIN M- McDOUGALL ATTORNEYS United States Patent 3,430,865 FQAM GENERATOR Franklin M. McDougail, Kirkwood, Mo., assignor to Standard Machine & Manufacturing Company, St. Louis, Mo., a corporation of Missouri Continuation of application Ser. No. 526,111, Feb. 9, 1966. This application Apr. 15, 1968. Ser. No. 721,515 US. Cl. 239-4275 3 Claims Int. Cl. B05b 7/00, 7/04; A47k 5/14 ABSTRACT OF THE DISCLOSURE A first injector, including a venturi having a constricted throat, interposed between an inlet and an outlet receives water under pressure. An induction passage communicates with the throat so that detergent is induced into the injector by pressure drop at the throat, there to be mixed with the water. The resulting mixture is discharged from the first injector into a second injector, which includes a second venturi. The second injector is substantially transverse to the first injector. The outlet of the first venturi communicates with a chamber ahead of the throat of the second venturi. An air nozzle communicates with the chamber to introduce air under positive pressure into the chamber so that the mixed water and detergent liquid are air entrained. The resultant stream is discharged through the second venturi and into the atmosphere to create a foam. Check valves disposed in the first venturi, the detergent induction passage, and the air nozzle, preclude reversal of flow at these locations.

This application is a continuation of application Ser. No. 526,111 filed Feb. 9, 1966, now abandoned.

This invention relates generally to improvements in a foam generator, and more particularly to a method of generating foam and to the apparatus utilized.

An important object is to provide a foam generator that is capable of producing a thick foam which can be applied directly to any surface, such foam adhering to the surface regardless of its shape, size or disposition. The generator is especially useful in cleaning walls of all types, and in cleaning vehicle bodies such as trucks, airplanes and automobiles. When used for such cleaning operations, the foam consists of water and detergent of predetermined proportions having a predetermined dryness.

It is an important object to provide a method of generating foam which comprises the steps of moving water under pressure through a venturi of a first injector, inducing liquid detergent into the water fiow substantially at the throat of the venturi of the first injector, feeding the resultant liquid stream of mixed water and detergent from the first injector into a second injector, moving air under pressure into the second injector, mixing and entraining the air with the liquid stream, and discharging the liquid stream and entrained air through a venturi of the second injector and from the second injector to the atmosphere to create a foam.

An important object is realized by feeding the resultant liquid stream of mixed water and detergent into the second injector ahead of the throat of the venturi of the second injector, and mixing and entraining the air with the liquid stream ahead of of the throat of the venturi of the second injector.

Another important object is afforded by inducing the liquid detergent into the water flow in a predetermined proportion, and mixing the air under pressure into entrainment with the proportioned liquid stream after the water and detergent have been proportioned and where there is a substantial amount of kinetic energy in the Patented Mar. 4, 1969 liquid stream. The air is placed into the liquid stream without sacrificing any of the liquid pressure.

Still another important object is attained by feeding the resultant liquid stream of mixed water and detergent into a chamber of the venturi of the second injector ahead of the venturi throat of the second injector, moving the air in a jet under pressure into the chamber and in a direction toward the venturi throat of the second injector, mixing and entraining the air with the liquid stream in the chamber, and discharging the liquid stream and entrained air primarily under the motive force of the liquid stream through the venturi of the second injector and from the second injector to the atmosphere to create the foam.

An important object is achieved by the provision of a foam generator apparatus in which a first injector includes a first venturi having a throat between an inlet and an outlet, the inlet being adapted for connection to a water source under pressure, and includes an induction passage having a port communicating with the throat of the first venturi, the induction passage being adapted for connection to a liquid detergent source so that the liquid detergent is induced into and mixed with the water flow to provide a resultant liquid stream discharged from the outlet of the first venturi. A second injector includes a second venturi having a throat between an inlet and an outlet. Means interconnects the first venturi outlet to the second venturi inlet to feed the liquid stream from the first injector to the second injector, and an air nozzle communicates with the second venturi inlet, the nozzle being adapted for connection to an air source under pressure so that the nozzle mixes and entrains air with the liquid stream. The liquid stream and entrained air is discharged through the second venturi throat and from the second venturi outlet to the atmosphere to create the foam.

Another important objective is provided by a structural arrangement of a chamber ahead of the second venturi throat into which the proportioned liquid stream is discharged by the first venturi outlet, and of the air nozzle directing an air jet into the chamber to mix and entrain the air with the liquid stream ahead of the second venturi throat, the liquid stream and entrained air being discharged through the second venturi throat and outlet primarily under the motive force of the liquid stream.

Yet another important object is realized by constructing the cross-sectional fiow area of the chamber so that it is at least as large as the cross sectional flow area of the first venturi outlet, whereby the air is mixed and entrained under pressure with the proportioned liquid stream at a point Where the liquid stream is under substantial pressure and before flow through the second venturi throat.

An important objective is afforded by communicating the first venturi outlet with the chamber laterally relative to the longitudinal flow axis passing through the second venturi throat, and by arranging the air nozzle so that it is directed into the chamber toward the second venturi throat and is substantially aligned with the longitudinal flow axis of the second venturi throat.

Another important objective is attained by the provision of a first check valve in the first venturi of the first injector ahead of the first venturi throat and the induction port so as to preclude reverse flow through the first venturi inlet, by the provision of a second check valve in the induction passage which precludes reverse flow from the first venturi throat through the induction port and induction passage, and by the provision of a third check valve in the air nozzle which precludes reverse flow through the nozzle from either the first venturi outlet or from the second venturi inlet.

A further important objective is to provide a foam generator apparatus that is simple and durable in construction, economical to manufacture and assemble, highly efficient in operation, and which can be utilized by any one with little or no instruction.

The foregoing and numerous other objects and advan tages of the invention will more clearly appear from the following detailed description of a preferred embodiment, particularly when considered in connection with the accompanying drawing, in which:

FIG. 1 is a side elevational view of the foam generator assembly;

FIG. 2 is an enlarged elevational view of the first and second injectors, the second injector and part of the first injector being shown in cross section, and

FIG. 3 is a cross-sectional view as taken along line 33 of FIG. 2.

Referring now by characters of reference to the drawing, and particularly to FIG. 1, it will be understood that the assembly of the foam generator includes a first injector generally indicated by secured and operatively connected to a second injector referred to by 11. The detailed construction of the first injector 10 is best illustrated in FIG. 3, while the detailed construction of the second injector 11 is best shown in FIG. 2.

From FIG. 3, it will be apparent that the first injector 10 includes an elongate body 12 having a first venturi generally indicated by 13 extending therethrough. This venturi 13 includes a narrow throat 14 between an inlet 15 and an outlet 16. The narrow venturi throat 14 is part of a bore through a plug 17 inserted into the first injector 10 and sealingly engaging the injector body 12. For convenience, the plug 17 can be removed and another corresponding plug having a venturi throat 14 of a different cross section can be substituted. The selective placement of a plug 17 having a predetermined venturi throat size is advantageous in regulating and controlling the minimum pressure in the venturi throat 14 desired or necessary in order to induce detergent into the first venturi 13, as will be later described.

The first injector body 12 includes a threaded end 20 containing the first venturi inlet 15. The body end 20 is partially threaded internally of the first venturi inlet 15 to receive and connect a cooperating nut 21. The nut 21 is provided with an inlet port 22 adapted to communicate with the first venturi inlet 15. A check valve is located in the first venturi 13 of the first injector 10. Specifically, the check valve includes a ball 23 constituting a valve member, located Within the first venturi inlet 15 and engaging the nut 21, constituting a valve seat 24 at the periphery of the inlet port 22. A compression spring 25 is disposed within the first venturi inlet 15, one end of the spring 25 engaging the ball 23, and the other end engaging the injector body 12 and plug 17. The spring 25 tends to urge the ball 23 against the valve seat 24 to close the inlet port 22.

Threadedly connected to the body end 20 is a pipe coupling 26 (FIG. 1). A hose adapter 27 is attached to the opposite end of the pipe coupling 26, the hose adapter 27 being connected to a hose 30, constituting a conduit, which is connected to a source of water under pressure. As will be understood, the maximum water pressure required with this foam generator assembly is approximately p.s.i.

Attached to the first injector body 12 is a detergent fitting referred tg-b'y 31 consisting of several interconnected parts. The detergent fitting 31 includes a tubular core 32 attached to the first injector body 12 adjacent the first venturi throat 14. The core 32 is provided with an internal bore 33 communicating with an induction port 34 formed in the first injector body 12 immediately opposite to and communicating with the first venturi throat 14 substantially in the region of the lowest pressure existing in the first venturi 13.

Fastened to the fitting core 32 is a meter cap 35 having an internal bore 36 extending therethrough and communicating with the core bore 33. The meter cap 35 has a threaded nipple 37 inserted into and threadedly connected to the fitting core 32. An O-ring 40 forms an effective seal between the fitting core 32 and meter cap 35.

Another check valve is disposed within the detergent fitting 31. Specifically, the check valve includes a ball 41, constituting a valve member, located within the bore 33 of fitting core 32, the ball 41 being adapted to close the cap bore 36, constituting a part of the detergent induction passage, by engaging an O-ring 42, constituting a valve seat, retained within the nipple 37. A compression spring 43 is located within the core bore 33, one end of the spring 43 engaging the ball 41, and the other end engaging the core 32. The spring 43 tends to urge the ball 41 against the O-ring 42 to close the detergent induction passage.

Threadedly connected to the meter cap 35 is a hose adapter 44 having an internal bore 45 that communicates with the bore 36 of meter cap 35. It will be understood that the operatively interconnected bores 33, 36 and 45, together with the induction port 34 form and constitute the detergent induction passage through the detergent induction fitting 31. As is indicated in FIG. 1, a hose 46 is operatively connected to the hose adapter 44. The opposite end of the detergent hose 46 is submerged in a liquid detergent or in any other liquid concentrate to be induced into the water flow through the first injector 10. The liquid detergent can be stored in any size shipping container (not shown).

A metering valve 47 is threaded-1y connected to the meter cap 35, the meter valve 47 extending across the bore 36. The cross sectional dimension of bore 36 and the body of meter valve 47 are related so that when the meter valve 47 is fully inserted, the body of such meter valve 47 will effectivel close the bore 36 to preclude any flow of detergent through the detergent induction passage. By backing off the meter valve 47, the bore 36 is opened to such a predetermined extent to control and regulate the amount of detergent fiow through the passage. Obviously, the metering valve 47 selectively regulates or meters the detergent flow through the detergent flow passage and into the first venturi 13 of the first injector 10, and thereby precisely regulates the proportion of water and detergent mixed in the first venturi 13.

The second injector 11 (FIG. 2) includes an elongate body 48 in which a second venturi referred to by 50 is formed. This second venturi 50 includes a relatively narrow throat 51 between an inlet 52 and an outlet 53.

The first injector body 12 includes a reduced end 54 in which the first venturi outlet 16 is located. The reduced body end 54 is fastened to the body 48 of the second injector 11 so that the first venturi outlet 16 communicates directly with the second venturi inlet 52. An O-ring 55 provides an effective seal between the end 54 of the first injector 10 and the bod 48 of the second injector 11.

The second venturi inlet includes a chamber 56 ahead of the second venturi throat 51. The cross sectional flow area of chamber 56 is at least as great as the cross sectional flow area of the first venturi outlet 16 so that the water pressure within the chamber 56 has a substantial value. The first venturi outlet 16 communicates with the chamber 56 laterally relative to the longitudinal flow axis passed through the second venturi throat 51.

An air injector generally indicated by 57 includes a nozzle 60 threadedly attached to the second injector body 48 and extending into the chamber 56. An O-ring 61 provides an effective seal between the nozzle 60 and the second injector body 48. The nozzle 60 introduces an air jet into the chamber 56 to mix and entrain air with the proportioned liquid stream passing into and through the chamber 56 from the first venturi 13 of the first injector 10 before the liquid stream passes through the second venturi throat 51. The air is mixed and entrained with the liquid stream in chamber 56 where there is a substantial amount of kinetic energy remaining in the liquid stream. In other words, the air is mixed and entrained into the liquid stream without sacrificing any of the liquid pressure.

The nozzle 60 is directed toward the second venturi throat 51 and is aligned with the longitudinal flow axis passed through the second venturi throat 51.

The nozzle 60 includes a threaded nipple 62 adapted to be connected to an air pressure regulator and gauge indicated by 63 and illustrated in FIG. 1. An air hose 64 is operatively connected to the pressure regulator and gauge 63, and thence is operatively connected to the nozzle 60. The air hose 64 is operatively connected to a compressed air source (not shown) capable of producing a maximum air pressure of 60 p.s.i.

A check valve is provided in the air injector 57 as is best seen in FIG. 2. The check valve includes a nut 65 threadedly attached to and located internall of the nipple 62. The nut 65 includes an inlet port 66 consituting of part of the air flow passage through the nozzle 60. A ball 67, constituting a valve member, is located within the nozzle 60 and is adapted to engage the nut 65 about the periphery of inlet port 66, constituting a valve seat 70. A compression spring 71 is located within the nozzle 60, one end of the spring 71 engaging the ball valve 67, and the other end of the spring 71 engaging the nozzle 60. The spring 71 tends to urge the ball 67 against the valve seat 70 to close the air passage through nozzle 60.

It is thought that the usage of the foam generator has become fully apparent upon the detailed description of parts, but for completeness of disclosure, the operation and functional advantages will be briefly described.

It will be assumed that the first injector is fixed to the second injector 11, that the detergent fitting 31 is fixed to the first injector 10, that the air injector 57 is fixed to the second injector 11, and that the pipe coupling 26 and air regulator and gauge 63 all have been assembled as illustrated in FIG. 1. The hose 30 connected to the first injector 10 is operatively connected to a source of Water supply to provide a water flow under pressure of approximately p.s.i. The detergent hose 46 is fastened to the hose adapter 44 and is placed in liquid detergent stored in a suitable container. The air hose 64 is connected to the regulator and gauge 63, and thence to the second injector 11, and is connected to a source of compressed air to provide an air pressure of approximately p.s.i. Any suitable hose or pipe (not shown) may be attached to the discharge end of the second injector 11, if desired, to direct and apply the discharged foam created by the generator onto the surface to be cleaned.

The water flows under pressure past the ball 23 and into the venturi inlet 15, and thence through the first venturi throat 14. Because the velocity of the water flow through the narrow first venturi throat 14 is increased, the pressure existing at such narrow throat 14 is correspondingl reduced so that the pressure differential existing in the detergent flow passage and the first venturi 13 at throat 14 causes or induces a detergent flow through the detergent hose 46 and into the detergent fitting 31 past the ball 41 and through the induction port 34. The meter valve 47 can be selectively adjusted to provide a predetermined flow rate for the liquid detergent moving through the detergent induction passage.

The liquid detergent is mixed with the water in a predetermined proportion, and the resultant, proportional liquid stream is discharged through the first venturi outlet 16 into the second venturi inlet 52, and thence into the venturi chamber 56 ahead of the narrow second venturi throat 51.

The source of compressed air provides air under pressure of approximately 60 p.s.i. through the regulator and gauge 63, and thence to the nozzle 60. The air under pressure flows past the ball 67 and is discharged in an air jet through the nozzle 60 into the venturi chamber 56 wherein the air is mixed and entrained with the proportioned liquid stream under conditions of relatively high liquid pressure. After the air has been mixed and entrained with the proportioned liquid stream in the venturi chamber 56, the liquid stream and entrained air flows through the second venturi throat '51 and through the second venturi outlet 53 primarily under the motive force of the liquid stream. Upon discharge of the liquid stream and entrained air to the atmosphere, a thick foam is created that can be applied to the surface to be cleaned, the foam adhering to such surface and facilitating cleaning operations.

The ball 23 precludes reverse water flow from the first venturi inlet 15 and induction port 34 back into the source of water supply. The ball 41 precludes reverse flow from the first venturi throat 14 and induction port 34 back through the detergent induction passage and into the supply of liquid detergent. The ball 67 precludes reverse flow through the nozzle '60 from either the first venturi outlet 16 or from the second venturi inlet 52'01' chamber 56.

Although the invention has been described by making detailed reference to a single preferred embodiment, such detail is to be understood in an instructive, rather than in any restrictive sense, many variants being possible within the scope of the claims hereunto appended.

I claim as my invention:

1. In a foam generator:

(a) a water source under pressure,

(b) a first injector including a first venturi having a throat between an inlet and an outlet,

(0) means connecting the first venturi inlet to the Water source,

(d) a liquid detergent source,

(e) the first injector including an induction passage having a port communicating laterally, substantially with the throat of the first venturi,

(f) means connecting the induction passage to the liquid detergent source, the liquid detergent being mixed with the water flow substantially at the first venturi throat to provide a resultant water-detergent stream discharged from the first venturi outlet,

(g) a second injector including a second venturi having a throat between an inlet and an outlet, the throat being substantially peripherally enclosed about the diameter,

(h) the second venturi inlet including a chamber ahead of the second venturi throat,

(i) the first venturi outlet communicating with the chamber laterally relative to the longitudinal flow axis of the second venturi throat, and discharging the water-detergent stream into the chamber for flow under pressure through the second venturi along the longitudinal flow axis,

(j) an air source under pressure,

(k) an air nozzle opening into the chamber in substantial alignment with the longitudinal axis of the second venturi throat, and

(1) means connecting the air nozzle to the air source,

(m) the air nozzle directing an air jet into the chamber, and into the water-detergent stream in the direction of flow along the longitudinal axis, the waterdetergent stream and entrained air being discharged along the longitudinal axis through the second venturi throat and from the second venturi outlet primarily under the motive force of the water-detergent stream and assisted by the air jet, to the atmosphere to create the foam.

2. In a foam generator:

(a) a first injector including a first venturi having a throat between an inlet and an outlet, the inlet being adapted for connection to a water source under pressure,

(b) the first injector including an induction passage having a port communicating substantially with the throat of the first venturi, the induction passage being adapted for connection to a liquid detergent source, the liquid detergent being mixed with the water flow to provide a resultant liquid stream discharged from the outlet of the first venturi,

(c) a second injector including a second venturi having a throat between an inlet and an outlet,

(d) means interconnecting the first venturi outlet to the second venturi inlet to feed the liquid stream of mixed water and detergent from the first injector to the second injector, and

(e) an air nozzle communicating with the second venturi inlet and adapted for connection to an air source under pressure, the nozzle mixing and entrainin air with the liquid stream, the liquid stream and entrained air being discharged through the second venturi throat and from the second venturi outlet to the atmosphere to create a foam,

(f) the second venturi inlet including a chamber ahead of ther second venturi throat,

(g) the first venturi outlet communicating with and discharging the proportioned liquid stream into the chamber,

(h) the air nozzle directing an air jet into the chamber, and mixing and entraining the air with the liquid stream ahead of the second venturi throat, the liquid stream and entrained air being discharged through the second venturi throat and outlet primarily under the motive force of the liquid stream to the atmosphere to create the foam,

(i) a first check valve being disposed in the first venturi of the first injector ahead of the first venturi throat and ahead of the induction port, the check valve precluding reverse flow through the first venturi inlet,

(j) a second check valve being disposed in the induction passage, precluding reverse flow from the first venturi throat through the induction port and passage, and

(k) a third check valve being disposed in the air nozzle precluding reverse flow through the nozzle from either the first venturi outlet or the second venturi inlet.

3. In a foam generator:

(a) a first injector including a first venturi having a throat between an inlet and an outlet, the inlet being adapted for connection to a water source under pressure,

(b) the first injector including an induction passage having a port communicating substantially with the throat of the first venturi, the induction being adapted for connection to a liquid detergent source, the liquid detergent being mixed with the water fiow to provide a resultant liquid stream discharged from the outlet of the first venturi,

(c) a second injector including a second venturi having a throat between an inlet and an outlet,

(d) means interconnecting the first venturi outlet to the second venturi inlet to feed the liquid stream of mixed water and detergent from the first injector to the second injector,

(e) an air nozzle communicating with the second venturi inlet and adapted for connection to an air source under pressure, the nozzle mixing and entraining air with the liquid stream, the liquid stream and entrained air being discharged through the second venturi throat and from the second venturi outlet to the atmosphere to create a foam,

(f) the first injector and the air nozzle being attached to the second injector,

(g) the second venturi inlet including a chamber ahead of the second venturi throat,

(h) the first venturi communicating with the chamber laterally relative to the longitudinal flow axis passed through the second venturi throat,

(i) the air nozzle extending into the chamber and being directed toward the second venturi throat and being substantially aligned with the longitudinal axis passed through the second venturi throat, the air nozzle mixing and entraining air under pressure into the proportioned liquid stream under pressure while in the chamber before passage through the second venturi throat,

(j) the cross sectional flow area of the chamber being at least as large as the first venturi outlet so that the air is mixed and entrained with the proportioned liquid stream when the liquid stream is under substantial water pressure and before flow through the second venturi throat, the proportioned liquid stream and entrained air being discharged through the second venturi throat and from the second venturi outlet to the atmosphere primarily under the motive force of the liquid stream to create the foam,

(k) a first check valve being disposed in the first venturi of the first injector ahead of the first venturi throat and ahead of the induction port, the first check valve precluding reverse flow through the first venturi outlet,

(1) a second check valve being disposed in the induction passage precluding reverse flow from the first venturi throat through the induction port and passage, and

(m) a third check valve being disposed in the air nozzle precluding reverse flow through the nozzle from either the first venturi outlet or the second venturi inlet.

References Cited 10/1939 Pedrick 239-9 4/1940 Urquhart 169--15 EVERETT W. KIRBY, Primary Examiner.

US. Cl. X.R. 

